Introduces a CHECK to analyze the crash reason.

chrome/browser/notifications/desktop_notification_service.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/browser/notifications/desktop_notification_service.h"
 
 #include "base/metrics/histogram.h"
 #include "base/prefs/scoped_user_pref_update.h"
 #include "base/strings/utf_string_conversions.h"
 #include "base/threading/thread.h"
@@ skipping 612 matching lines @@
         new WelcomeNotification(profile_, g_browser_process->message_center()));
   }
 
   if (welcome_notification)
     welcome_notification->ShowWelcomeNotificationIfNecessary(notification);
 }
 
 void DesktopNotificationService::OnStringListPrefChanged(
     const char* pref_name, std::set<std::string>* ids_field) {
   ids_field->clear();
-  const base::ListValue* pref_list = profile_->GetPrefs()->GetList(pref_name);
+  // Separate GetPrefs()->GetList() to analyze the crash. See crbug.com/322320
+  const PrefService* pref_service = profile_->GetPrefs();
+  CHECK(pref_service);
+  const base::ListValue* pref_list = pref_service->GetList(pref_name);
   for (size_t i = 0; i < pref_list->GetSize(); ++i) {
     std::string element;
     if (pref_list->GetString(i, &element) && !element.empty())
       ids_field->insert(element);
     else
       LOG(WARNING) << i << "-th element is not a string for " << pref_name;
   }
 }
 
 void DesktopNotificationService::Observe(
@@ skipping 29 matching lines @@
   // Tell the IO thread that this extension's permission for notifications
   // has changed.
   extensions::InfoMap* extension_info_map =
       extensions::ExtensionSystem::Get(profile_)->info_map();
   BrowserThread::PostTask(
       BrowserThread::IO, FROM_HERE,
       base::Bind(&extensions::InfoMap::SetNotificationsDisabled,
                  extension_info_map, notifier_id.id, !enabled));
 
 }